The invention relates to an apparatus for controlling the flow of an infusion fluid in an infusion system with a drip chamber and a deformable tube, said apparatus comprising a sensor for detecting the drops of infusion fluid falling in the drip chamber, means for setting a desired flow rate, pinch clamp means for pinching off the deformable tube and a processing unit for controlling the pinch clamp means in dependence on the set desired flow rate and the signal of the sensor.
Such apparatus are known in various embodiments and are for example disclosed in U.S. Pat. Nos. 4,507,112 and 4,525,163. In such apparatus the accuracy of controlling the pinch clamp means is of great importance. The embodiment described in U.S. Pat. No. 4,507,112 appears not to have a satisfactory operation in practice. The apparatus disclosed in U.S. Pat. No. 4,525,163 uses a drip chamber formed in a special manner in which a closing element is provided.
The invention aims to provide an apparatus of the above-mentioned type, by which the flow rate of an infusion fluid can be controlled in a very accurate manner in an infusion system equipped with a conventional drip chamber.